Double-sided thermostatic fabric and preparation method thereof

ABSTRACT

A double-sided thermostatic fabric and a preparation method thereof are provided. The preparation method includes: preparing a light-reflecting heat-insulated fiber (namely a second fiber), and performing laser etching on a surface of the light-reflecting heat-insulated fiber to obtain a helical fiber, the helical fiber having good light reflection and heat reflection, and serving as an outer layer of the fabric; preparing a modified hemp fiber, the modified hemp fiber having good unidirectional moisture conduction and heat conduction, and serving as an inner layer of the fabric; and compositing the inner layer and the outer layer by connecting a back warp to a face weft, thereby forming the double-sided fabric. By modifying a surface structure of the fiber and performing modification on the fiber, the prepared fabric can realize temperature reduction through heat radiation and unidirectional moisture conduction in hot weathers, and realize heat preservation through heat reflection in cold weathers.

CROSS REFERENCE TO THE RELATED APPLICATIONS

This application is the national phase entry of International Application No. PCT/CN2022/084895, filed on Apr. 1, 2022, which is based upon and claims priority to Chinese Patent Application No. 202111166553.0, filed on Sep. 30, 2021, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to the technical field of textiles, and in particular to a double-sided thermostatic fabric and a preparation method thereof.

BACKGROUND

Due to the greenhouse effect and urban heat island effect, global warming has been exacerbated, extreme weathers has become more frequent, and there have been more scorching weathers and higher temperatures in summer. As a result of the scorching weathers, the use and demand of cooling devices and air-conditioning heat pump devices are increasing year by year. However, with intensive use of the conventional cooling devices, huge energy consumption is caused. Specifically, working media such as chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) have a destructive effect on the ozone layer. Hence, research on novel environment-friendly cooling products has become an important topic to protect the environment and improve the quality of people's lives. Thermostatic fabrics can control the temperature of bodies through radiative cooling and heat reflection, which is considered as a convenient and effective heat management method for energy conservation and environmental protection.

The thermostatic fabrics are mainly intended to use technologies such as radiative cooling, heat reflection and temperature-varying materials to maintain human skin at a comfortable contact temperature, namely, to keep it warm in cold weathers and cool in hot weathers. Most energy from solar radiation is concentrated in regions of visible light and infrared light. Based on material selection and structural design, a fabric with a high reflectivity at a solar radiation band of 0.3-2.5 μm and a high emissivity at a body radiation band of 7-14 μm is manufactured. Hence, the body exchanges radiant heat with the low-temperature outer space and the high-level atmospheric layer through an “atmospheric window”, thereby obtaining a cooling effect. With reinforced materials for reflecting sunlight, transmission and absorption of the sunlight are reduced. This can reduce heat accumulation for the solar radiation, and make ultraviolet rays less harmful to the human health.

The China's Taiwan invention patent TWI707906B provides a graphene thermostatic fabric. According to the present disclosure, by combining graphene having special thermal properties and excellent electrical conductivity with a solvent having a low boiling point and a high surface tension, a graphene nanosheet suspension is prepared. The graphene nanosheet suspension is mixed with hydrophobic resin to prepare a graphene resin solution. Through coating or printing, the graphene resin solution covers and penetrates into fabric weaves, thereby forming a graphene thermostatic layer. In response to a high ambient temperature, the graphene thermostatic layer can accelerate heat dissipation from human skin to achieve a cooling effect. In response to a low ambient temperature, the graphene thermostatic layer can make temperatures at different parts of the human skin uniform, and further absorb and release far infrared rays radiated by the human skin, thereby achieving warming and thermostatic effects. However, consequences in long-term contact with the graphene are unclear hitherto. The safety of the graphene applied to body-contacting fabrics cannot be ensured. Moreover, the graphene causes serious environmental pollution in preparation.

The US invention patent US11058161B2 provides a heat reflecting fabric. The fabric includes at least a metal layer. The metal layer can form a radiant barrier to reduce a heat loss via radiation from the human body. The metal layer is combined with a three-dimensional (3D) warp knit fabric with good air gaps to expose the low emissivity surface of the metal layer. The 3D warp knitted fabric also has a predetermined thickness to provide insulation between the metal layer and other surfaces. The fabric can reduce the heat loss from the body by reflecting the body heat back in the system. However, only with the heat preservation effect, the fabric cannot reduce the body temperature in hot weathers to realize a thermostatic effect.

The Chinese invention patent CN104127279B provides a multifunctional temperature-adjusting film. From outside to inside, the multifunctional temperature-adjusting film includes a functional material carrier layer and a heat preservation layer close to a skin. The functional material carrier layer is made of a water-proof flexible material to form a sealed cavity structure and is provided with a chemical cooling or heating material. The heat preservation layer is made of a material with water resistance and heat preservation. If the chemical heating material is used, the functional material carrier layer can take a heating effect. If the chemical cooling material is used, the heat preservation layer can prevent a local cold injury. Uniform and stable heat exchange occurs between the functional material carrier layer and the skin to achieve a long-acting cooling effect. However, due to the lack of air permeability and water permeability, and the time-dependent temperature control, the film cannot be applicable to common garments.

The Chinese utility model patent CN211747098U provides a thermostatic air-conditioning garment. The air-conditioning garment includes an upper garment made of a textile, a temperature adjustment module, a temperature detection sensor, a control module, and a lithium battery pack. A semiconductor cooling plate and a cooling fan are used for cooling and are provided therebetween with a heat sink. The control module is connected to the lithium battery pack, the temperature adjustment module, and the temperature detection sensor. The lithium battery pack serves as a power supply. The temperature detection sensor is used for detecting a temperature and feeding temperature information back to the control module. The control module starts the temperature adjustment module according to a set temperature for cooling or heating. In spite of good cooling and heating functions, the garment is restricted by a complicated manufacturing process and a high cost and cannot realize zero-energy personal thermal management.

The Chinese invention patent CN113136724A provides a radiative cooling fabric. The fabric contains a silk fiber. The radiative cooling fabric includes a material attached to the fiber and having a refractive index of higher than 1.6 and less than 3.0. The material attached to the fiber and having the high refractive index overlaps with the fiber to improve an ultraviolet reflectivity. Compared with an untreated fabric, the ultraviolet reflectivity is increased by 42%, and the reflectivity in the whole solar band is up to 95%. The temperature of the treated fabric in the sunlight can be lower than the room temperature by about 3.6° C. When covering the skin, the radiative cooling fabric can reduce the temperature by about 12° C. over the cotton fabric. However, the fabric does not have heat preservation effect, and cannot create a thermostatic environment in case of a low temperature.

To sum up, it is desired to provide a convenient, efficient and energy-saving method to prepare a thermostatic fabric with heat preservation and cooling function and make the thermostatic fabric applicable to the common garments for the personal thermal management.

SUMMARY

In view of this, embodiments of the present disclosure provide a double-sided thermostatic fabric and a preparation method thereof, to solve the technical defects in the prior art.

The present disclosure provides a double-sided thermostatic fabric, including a first fiber and a second fiber, where the first fiber is a hemp fiber; the second fiber is a helical fiber with a threaded groove in a surface; the first fiber and the second fiber are composited to form the fabric; one side of the fabric is the first fiber, and the other side of the fabric is the second fiber; and when the fabric is worn, both the first fiber side and the second fiber side may face inward or outward.

Further, the hemp fiber (natural hemp fiber) is a modified hemp fiber.

Further, the second fiber includes a polyester fiber and a sun-protective light-reflecting coating covering the polyester fiber; and the helical groove is formed in an outer side of the sun-protective light-reflecting coating.

Further, the sun-protective light-reflecting coating includes alkyd resin and a sun-protective nanoparticle, and a mass ratio of the alkyd resin to the sun-protective nanoparticle is 1:(0-0.3).

Further, the alkyd resin is silicone-modified alkyd resin; and preferably, the silicone-modified alkyd resin is obtained by copolycondensation of polyalkyl silicone resin, polyaryl silicone resin or polyalkylaryl silicone resin with the alkyd resin.

Further, an outer surface of the helical fiber is of a threaded form; the threaded form is a trapezoid, a rectangle or a triangle; and preferably, the threaded form has a thread angle of 0-30°, a width of 0.1-3.0 μm from a crest to a root, and a pitch of 0.1-5.0 μm.

Further, the sun-protective nanoparticle has a particle size of 0.5-10 μm.

The present disclosure further provides a preparation method of the double-sided thermostatic fabric, including the following steps:

preparation of the second fiber: method 1: (1) melting the alkyd resin or dissolving the alkyd resin in a solvent, adding the sun-protective nanoparticle, and performing stirring for 20-60 min; (2) allowing a substance obtained in step (1) to form a viscous semisolid; (3) completely removing the solvent or performing cooling to form a solid thin film, thereby obtaining the sun-protective light-reflecting coating; and (4) allowing the sun-protective light-reflecting coating to cover the polyester fiber; and

method 2: (1) performing a same operation as step (1) of method 1; (2) allowing the substance obtained in step (1) to form the viscous semisolid; and (3) coating the viscous semisolid obtained in step (2) on the polyester fiber; and

preparation of the double-sided thermostatic fabric: knitting the first fiber and the second fiber according to any one of Implementations 1 to 8 into the double-layer fabric.

Further, in method 1, the threaded groove is formed in the sun-protective light-reflecting coating obtained in step (3).

Further, in step (2) of method 1 or method 2, the viscous semisolid is formed as follows: A: adding a thickening agent; B: removing a part of the solvent if the alkyd resin is dissolved; and C: performing, if the alkyd resin is molten, the cooling to form the viscous semisolid.

Further, a binder is added in step (1) of method 1 or method 2; and the binder includes at least one of styrene-butadiene rubber (SBR), chloroprene rubber and nitrile-butadiene rubber (NBR).

According to the above technical solutions, the present disclosure at least achieves the following advantages: The double-sided thermostatic fabric is reversible, namely, an outer side of the double-sided thermostatic fabric can face outward, and can also face inward; and correspondingly, an inner side of the double-sided thermostatic fabric can face inward, and can also face outward. Different wearing ways have different effects.

The silicone-modified alkyd resin has excellent light reflection, heat insulation, outdoor weather resistance and ultraviolet resistance. The sun-protective nanoparticle prepared with a homogeneous precipitation method is added to the silicone-modified alkyd resin according to a certain proportion, thereby further improving the sun protection and light reflection. The threaded structure can enhance reflection for sunlight at different incident angles. The hemp fiber not only keeps characteristics of the original hemp fiber in looseness, air permeability, fast heat transmission, coolness, smoothness, sweat resistance, insect and mold prevention, and little static electricity, but also has hydrophobicity and better moisture conduction and dissipation. Without designing more moisture permeable and air permeable holes or reducing a fabric density, the fabric has good moisture conduction and air permeation. The fabric still has good heat preservation when worn reversibly. Hence, both sides of the double-sided thermostatic fabric can be worn. The fabric realizes temperature reduction at a high temperature through heat radiation and unidirectional moisture conduction, or heat preservation at a low temperature through heat reflection. The double-layer fabric structure improves the heat dissipation and air permeation. By introducing random nanostructures such as air gaps, medium particles, and polymer nanofibers to the fabric, strong Mie scattering is achieved, thereby efficiently adjusting the solar radiation band. By improving the synthetic fiber and the natural fiber and performing blending, the fabric is more comfortable. Meanwhile, based on different moisture permeabilities of the synthetic fiber and the natural fiber, the unidirectional hygroscopic fabric can be achieved, and the fabric is drier and more comfortable.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to make the objectives, technical solutions and beneficial effects of the present disclosure clearer, the present disclosure provides the following drawings:

FIGURE is a schematic structural view of a helical groove according to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The specific implementations of the present disclosure will be described below with reference to the accompanying drawings.

The specific implementations of the present disclosure will be described below with reference to the accompanying drawings.

In the present disclosure, unless otherwise specified, the scientific and technical terms used herein have the meanings commonly understood by those skilled in the art. Meanwhile, agents, materials and steps used herein are widely used agents and materials, and common steps in the corresponding field.

Embodiment 1

The embodiment provides a double-sided thermostatic fabric capable of adjusting a temperature, including a first fiber and a second fiber. The first fiber and the second fiber are composited to form a double-layer fiber structure. The composition method may refer to a double-layer composition method in the prior art. Preferably, an inner layer and an outer layer are composited by connecting a back warp to a face weft, thus forming the double-sided fabric.

The first fiber is a hemp fiber, preferably a natural hemp fiber. The second fiber is a helical fiber with a threaded groove in a surface.

As a further preferred implementation, the hemp fiber is preferably a modified hemp fiber. The natural hemp fiber is healthier and more hygroscopic. The modified hemp fiber has better heat conduction, while keeping hygroscopic. Preferably, the modified hemp fiber is obtained by graft copolymerization of the hemp fiber onto poly (butylene succinate) (PBS). In this case, the modified hemp fiber has good unidirectional moisture conduction and heat conduction. The modified hemp fiber serves as the inner layer of the fabric, with strong practicability and good effect.

As a further preferred implementation, the hemp fiber is preferably modified as follows: The hemp fiber is pretreated with a potassium permanganate solution. With decahydronaphthalene as a solvent, succinic acid and butanediol are mixed with a catalyst SnC12, reacted for 1-2 h at 150-160° C. till complete esterification, and heated to 190-200° C. The pretreated hemp fiber is added for graft copolymerization. Heat preservation is performed for 10-12 h to obtain the modified hemp fiber.

As a further preferred implementation, the second fiber has a fineness of 2.0 dtex-5.0 dtex such as 2.0 dtex, 2.5 dtex, 3.0 dtex, 3.5 dtex, 4.0 dtex, 4.5 dtex and 5.0 dtex, and a diameter of 15.0-30.0 μm. The fiber with the fineness in this range can meet applications of the present disclosure.

As a further preferred implementation, the second fiber includes a polyester fiber and a sun-protective light-reflecting coating covering the polyester fiber. The helical groove is formed in an outer side of the sun-protective light-reflecting coating. Preferably, the polyester fiber is polyethylene terephthalate (PET).

As a further preferred implementation, the sun-protective light-reflecting coating includes alkyd resin and a sun-protective nanoparticle, and a mass ratio of the alkyd resin to the sun-protective nanoparticle is 1:(0-0.3).

The alkyd resin is preferably silicone-modified alkyd resin.

As a further preferred implementation, the silicone-modified alkyd resin is obtained by copolycondensation of polyalkyl silicone resin, polyaryl silicone resin or polyalkylaryl silicone resin with the alkyd resin.

As a further preferred implementation, an outer surface of the helical fiber is of a threaded form. The threaded form is a trapezoid, a rectangle or a triangle, more preferably the trapezoid and the rectangle, and most preferably the trapezoid.

As a further preferred implementation, the threaded form has a thread angle of 0-30°, preferably 17-23°, such as 17°, 18°, 19°, 20°, 21°, 22° and 23°, a width of 0.1-3.0 μm from a crest to a root, preferably 0.2-1 μm, such as 0.2 μm, 0.4 μm, 0.6 μm, 0.8 μm and 1.0 μm, and a pitch of 0.1-5.0 μm, preferably 0.5-2 μm, such as 0.5 μm, 0.8 μm, 1.0 μm, 1.3 μm, 1.5 μm, 1.8 μm and 2.0 μm.

As a further preferred implementation, the sun-protective nanoparticle has a particle size of 0.5-10 μm, preferably 2-6 μm. The nanoparticle with the particle size in this range can balance sun protection performance and a specific surface area. The nanoparticle with a smaller particle size has undesirable sun protection performance or effect, and the nanoparticle with a larger size has a small specific surface area to affect the sun protection performance. More importantly, by introducing the nanoparticle with such a particle size to the silicone-modified alkyd resin, strong Mie scattering can be achieved to efficiently control the solar radiation band, and better adjust the temperature.

As a further preferred implementation, the sun-protective nanoparticle includes one or more of TiO2, ZnO, SiO2, ZrO2, CeO2, MgO, Al2O3, Fe2O3, Fe3O4, MgSiO3, Al2SiO5, BaCO3, BaSO4, jade powder, mica powder, quartz sand, dolomite, agalmatolite, borneol, calcium silicate, polyethylene (PE), TiO2, ZnO, SiO2, ZrO2, CeO2, MgO, Al2O3, Fe2O3, Fe3O4, MgSiO3, Al2SiO5, BaCO3, BaSO4, ZrN, AlN, SiN, BN, Si3N4, SiC, Zn(NO3)2, phenolic resin, bismaleimide resin, graphite, carbon nanotube, aluminum-carbon nanotube, fluororesin, tetrafluoroethylene, silicone-modified acrylic resin or fluorocarbon resin, trifluorochloroethylene, salicylate, diphenyl ketone, benzotriazole, triazine, trimethoxybenzoate, para-aminobenzoic acid, phenyl cinnamate, camphor derivative, tetrafluoroethylene and perfluoro-2,2-dimethyl-1,3-dioxole copolymer, and benzoxazinone in benzamidine.

According to the solutions in the embodiment, the fabric has a certain temperature adjusting function, and can keep a desirable thermostatic state.

In response to hot weathers with strong sunlight, the second fiber can face outward for wearing. The special sun-protective coating on the second fiber has a high reflectivity at a solar radiation band. More importantly, the special helical groove is formed in the side of the second fiber. Particularly, in response to the thread angle of 17-23°, radiated sunlight is reflected and refracted efficiently in the groove, and further diffused to some extent. This plays an important role in temperature reduction. In the second fiber, the alkyd resin, particularly the silicone-modified alkyd resin, has strong heat insulation, and can prevent outside high temperature from entering the body to a great extent. With the special reflection of the sun-protective coating, the special structure of the helical groove, and the alkyd resin, the fabric has desirable temperature reduction and temperature control effects. The natural modified hemp fiber at the inner side further has strong moisture absorption, heat absorption and unidirectional moisture conduction. This also facilitates the temperature reduction, and makes the body more comfortable. To sum up, the fabric has desirable heatstroke prevention.

In response to the cold weathers, the second fiber faces inward preferably for wearing. Because the solar radiation band does not overlap with the body radiation band, the special sun-protective coating on the second fiber has high heat absorption at the body radiation band, and can preserve heat in reverse wearing. In the second fiber, the alkyd resin, particularly the silicone-modified alkyd resin, has strong heat insulation, and can prevent a loss of the body temperature to a great extent. More importantly, the hemp fiber at the outer side has good light absorption, and better keeps or accelerates the body temperature.

In the embodiment, in combination with the sun-protective particle having the special size, the silicone-modified alkyd resin and the special helical fiber, the temperature control effect and overall comprehensive effect of the fabric are greatly improved.

Embodiment 2

On the basis of Embodiment 1, the embodiment provides a preparation method of the double-sided thermostatic fabric, including the following steps:

Preparation of the second fiber: method 1: (1) The alkyd resin is molten or is dissolved in a solvent (the dissolvability is 60-100%, namely the alkyd resin may not be dissolved completely). Under heating, the sun-protective nanoparticle is added, and stirring is performed for 20-60 min. (2) A substance obtained in step (1) forms a viscous semisolid. (3) The solvent is removed completely or cooling is performed to form a solid thin film, thereby obtaining the sun-protective light-reflecting coating. (4) The sun-protective light-reflecting coating covers the polyester fiber. Herein, the alkyd resin may be dry resin or semi-dry resin. The solvent is an esters solvent, an alcohols solvent and a ketones solvent, provided that a part of the alkyd resin can be dissolved.

Method 2: (1) A same operation as step (1) of method 1 is performed. (2) A substance obtained in step (1) forms a viscous semisolid. (3) The viscous semisolid obtained in step (2) is coated on the polyester fiber.

Preparation of the double-sided thermostatic fabric: The first fiber and the second fiber are knitted into the double-layer fabric. The knitting method refers to a method for knitting a double-layer fabric in the prior art. Preferably, inner layer and the outer layer are composited by connecting a back warp to a surface weft.

As a further preferred implementation, in method 1, the threaded groove is formed in one side of the sun-protective light-reflecting coating obtained in step (3). Preferably, the helical fiber formed by laser engraving or etching on the surface of the second fiber has good light reflection and heat reflection, and serves as the outer layer of the fabric.

As a further preferred implementation, a binder is added in step (1) of method 1 or method 2. The binder includes at least one of SBR, chloroprene rubber and NBR.

As a further preferred implementation, in step (2) of method 1 or method 2, the viscous semisolid is formed as follows: A: A thickening agent is added. B: A part of the solvent is removed if the alkyd resin is dissolved, namely the operation of removing the solvent is stopped in response to colloidal resin. C: If the alkyd resin is molten, the cooling is performed to form the viscous semisolid.

Embodiment 3

Experimental example: The double-sided thermostatic fabric is prepared according Embodiment 2 of the present disclosure.

Comparative Example 1: The sun-protective light-reflecting coating in the experimental example is not provided. Other processes are the same as those in the experimental example.

Comparative Example 2: The sun-protective nanoparticle in the experimental example is not added. Other processes are the same as those in the experimental example.

Comparative example 3: The alkyd resin in the experimental example is not added. Instead, the polyester fiber is placed into a padder, and immersed in a sun-protective nanoparticle solution. Through padding of a padding roller set, the sun-protective nanoparticle is pressed into a structural surface of the polyester fiber in a micro-nano manner. Drying is performed to obtain the polyester fiber with the sun-protective nanoparticle. Other processes are the same as those in the experimental example.

Comparative Example 4: The helical groove in the experimental example is modified as a rough structure with a plurality of bumps on a surface. Other processes are the same as those in the experimental example.

Comparative Example 5: The modified hemp fiber in the experimental example is modified as the hemp fiber. Other processes are the same as those in the experimental example.

Experimental method: 1. At 10° C., a hot-water bag was used to simulate the body. The hot-water bag was respectively covered by the double-sided thermostatic fabrics in Embodiment 1 and Comparative Examples 1-5 to measure a temperature of the hot-water bag over time, thereby reflecting heat preservation of different double-sided thermostatic fabrics.

Test results are shown in a table below:

Initial Temperature Temperature temperature at 15 min at 30 min (° C.) (° C.) (° C.) Experimental Example 50.0 41.5 34.6 Comparative Example 1 50.0 36.4 29.2 Comparative Example 2 50.0 38.5 31.0 Comparative Example 3 50.0 37.0 30.5 Comparative Example 4 50.0 40.8 34.0 Comparative Example 5 50.0 39.3 33.7

2. The double-sided thermostatic fabrics in Embodiment 1 and Comparative Examples 1-5 were tested respectively in reflectivity and emissivity for sunlight, thereby reflecting the cooling effect.

Test results are shown in a table below:

Emissivity of an Reflectivity at atmospheric radiation a solar band window at a of 0.3-2.5 μm band of 8-13 μm Experimental Example 92% 0.93 Comparative Example 1 77% 0.85 Comparative Example 2 83% 0.87 Comparative Example 3 88% 0.90 Comparative Example 4 90% 0.85 Comparative Example 5 87% 0.86

3. The double-sided thermostatic fabrics in Embodiment 1 and Comparative Examples 1-5 were tested respectively in air permeability, specifically: A test sample was clamped onto an air-permeability tester with a constant-pressure-difference flow measurement method. A pressure was adjusted to form a constant pressure difference between two sides of the test sample. An airflow vertically passing through a given area of the test sample within a certain time was measured to obtain the air permeability (L/h) of different double-sided thermostatic fabrics.

Air permeability (L/h) Experimental Example 23.8 Comparative Example 1 24.9 Comparative Example 2 23.5 Comparative Example 3 24.3 Comparative Example 4 20.0 Comparative Example 5 18.7

From the above, the present disclosure has desirable temperature adjusting function and air permeability.

In the present disclosure, the double-sided thermostatic fabric can be produced in batches. By modifying a surface structure of the fiber and performing modification on the fiber, the fabric can realize temperature reduction through heat radiation and unidirectional moisture conduction in hot weathers, and realize heat preservation through heat reflection in cold weathers. The present disclosure can be applied to manufacture of body temperature-controlled garments.

In the present disclosure, terms such as “upper”, “lower”, “front”, “rear”, “left” and “right” are only intended to represent a relative position relationship between associated portions, rather than limit absolute positions of these associated portions.

In the present disclosure, terms such as “first” and “second” are only used to make a distinction from each other, rather than indicate a degree of importance, a sequence and a prerequisite for each other.

In the present disclosure, terms such as “equal” and “same” are not strictly mathematical and/or geometrical limitations, and further include allowable errors understood and manufactured or used by those skilled in the art.

Unless otherwise specified, a numerical range used herein includes not only the whole range between the two endpoints, but also a plurality of subranges therein.

The preferred specific implementations and embodiments of the present disclosure are described in detail above, but the present disclosure is not limited to the above implementations and embodiments. Within the knowledge of those skilled in the art, various variations can also be made without departing from the concept of the present disclosure. 

What is claimed is:
 1. A double-sided thermostatic fabric, comprising a first fiber and a second fiber, wherein the first fiber is a hemp fiber; the second fiber is a helical fiber with a threaded groove in a surface; and the first fiber and the second fiber are composited to form the double-sided thermostatic fabric; one side of the double-sided thermostatic fabric is the first fiber, and the other side of the double-sided thermostatic fabric is the second fiber; and when the double-sided thermostatic fabric is worn, both the first fiber side and the second fiber side face inward or outward.
 2. The double-sided thermostatic fabric according to claim 1, wherein the second fiber has a fineness of 2.0 dtex-5.0 dtex; and the second fiber is the helical fiber prepared by laser engraving or etching on the surface and provided with the threaded groove.
 3. The double-sided thermostatic fabric according to claim 1, wherein the hemp fiber is a modified hemp fiber.
 4. The double-sided thermostatic fabric according to claim 3, wherein the second fiber comprises a polyester fiber and a sun-protective light-reflecting coating covering the polyester fiber; and a helical groove is formed in an outer side of the sun-protective light-reflecting coating.
 5. The double-sided thermostatic fabric according to claim 4, wherein the sun-protective light-reflecting coating comprises alkyd resin and a sun-protective nanoparticle, and a mass ratio of the alkyd resin to the sun-protective nanoparticle is 1:(0-0.3).
 6. The double-sided thermostatic fabric according to claim 5, wherein the alkyd resin is silicone-modified alkyd resin; and preferably, the silicone-modified alkyd resin is obtained by copolycondensation of polyalkyl silicone resin, polyaryl silicone resin or polyalkylaryl silicone resin with the alkyd resin.
 7. The double-sided thermostatic fabric according to claim 6, wherein an outer surface of the helical fiber is of a threaded form; the threaded form is a trapezoid, a rectangle or a triangle; and preferably, the threaded form has a thread angle of 0°-30°, a width of 0.1 μm-3.0 μm from a crest to a root, and a pitch of 0.1 μm-5.0 μm.
 8. The double-sided thermostatic fabric according to claim 7, wherein the sun-protective nanoparticle has a particle size of 0.5 μm-10 μm.
 9. A preparation method of the double-sided thermostatic fabric according to claim 1, comprising the following steps: preparation of the second fiber: a first method comprises: (1) melting an alkyd resin or dissolving the alkyd resin in a solvent, adding a sun-protective nanoparticle, and performing stirring for 20 min-60 min; (2) allowing a substance obtained in step (1) to form a viscous semisolid; (3) completely removing the solvent or performing cooling to form a solid thin film, thereby obtaining a sun-protective light-reflecting coating; and (4) allowing the sun-protective light-reflecting coating to cover a polyester fiber; and a second method: (1) performing a same operation as step (1) of the first method; (2) allowing the substance obtained in step (1) to form the viscous semisolid; and (3) coating the viscous semisolid obtained in step (2) on the polyester fiber; and preparation of the double-sided thermostatic fabric: knitting the first fiber and the second fiber into the double-layer fabric.
 10. The preparation method according to claim 9, wherein in the first method, the threaded groove is formed in the sun-protective light-reflecting coating obtained in step (3); preferably, in step (2) of the first method or the second method, the viscous semisolid is formed as follows: A: adding a thickening agent; B: removing a part of the solvent if the alkyd resin is dissolved; and C: performing, if the alkyd resin is molten, the cooling to form the viscous semisolid; and preferably, a binder is added in step (1) of the first method or the second method; and the binder comprises at least one of styrene-butadiene rubber (SBR), chloroprene rubber and nitrile-butadiene rubber (NBR).
 11. The preparation method according to claim 9, wherein in the double-sided thermostatic fabric, the second fiber has a fineness of 2.0 dtex-5.0 dtex; and the second fiber is the helical fiber prepared by laser engraving or etching on the surface and provided with the threaded groove.
 12. The preparation method according to claim 9, wherein in the double-sided thermostatic fabric, the hemp fiber is a modified hemp fiber.
 13. The preparation method according to claim 12, wherein in the double-sided thermostatic fabric, the second fiber comprises a polyester fiber and a sun-protective light-reflecting coating covering the polyester fiber; and a helical groove is formed in an outer side of the sun-protective light-reflecting coating.
 14. The preparation method according to claim 13, wherein in the double-sided thermostatic fabric, the sun-protective light-reflecting coating comprises alkyd resin and a sun-protective nanoparticle, and a mass ratio of the alkyd resin to the sun-protective nanoparticle is 1:(0-0.3).
 15. The preparation method according to claim 14, wherein in the double-sided thermostatic fabric, the alkyd resin is silicone-modified alkyd resin; and preferably, the silicone-modified alkyd resin is obtained by copolycondensation of polyalkyl silicone resin, polyaryl silicone resin or polyalkylaryl silicone resin with the alkyd resin.
 16. The preparation method according to claim 15, wherein in the double-sided thermostatic fabric, an outer surface of the helical fiber is of a threaded form; the threaded form is a trapezoid, a rectangle or a triangle; and preferably, the threaded form has a thread angle of 0°-30°, a width of 0.1 μm-3.0 μm from a crest to a root, and a pitch of 0.1 μm-5.0 μm.
 17. The preparation method according to claim 16, wherein in the double-sided thermostatic fabric, the sun-protective nanoparticle has a particle size of 0.5 μm-10 μm. 